Electric mat switch



p 1952 s. s. ROBY 2,611,049

ELECTRIC MAT SWITCH Filed Aug. 22, 1950 2 SHEETSSHEET 1 I u I Gttomegs Sept. 16, 1952 OBY 2,611,049

ELECTRIC MAT SWITCH Filed Aug. 22, 1950 2 SHEETS-SHEET 2 Zhwentor SHELL? ON 07 ROB) I Patented Sept. 16 1952 ELECTRIC MAT SWITCH Sheldon S. Roby, Meriden, Conn, assignor to The Stanley Works, New Britain,'Conn., a corporation of 7 Connecticut Application August 22, 1950, Serial No. 130,860

The present invention relates generally to means for controlling the operation of automatically operated doors and thelike, and more particularly to an improved electric mat switch for such use having improved operating characteristics and yet simple and economical in construction so that it may be easily fabricated and assembled at relatively low cost.

It is an object of the present invention to provide an electric mat switch for use in installations or automatically operated doors and the like which will have a uniformly high degree of sensitivity throughout its full area so'that an electrical circuit through the electric mat switch will be established at substantially the same pressure throughout regardless of the particular area of the mat which is stepped upon or otherwise actuated without at the same time being sensitive to vibrations or pressures not resulting from intended operation of theswitch tending to cause the contacting members to close.

A further object of the invention is to provide an electric mat switch of the character referred to which will be of economical construction so that it may be fabricated and assembled without complicated hand operations and without the need for careful and skilled workmanship with the result that the mat may be made at low cost.

A further object of the invention isto provide anelectric mat switch having .the characteristics referred to which will retain these characteristics over long periods of time so that the switch will operate effectively and efiiciently afterlong, periods of use and without change.

Other objects will be in part obvious, and in part pointed out more in detail'hereinafter.

The invention accordingly consists in the features of a construction, combination of elements and arrangement of parts which will be exemplified in the construction hereafter set forth and the scope of the application of which will be indicated in the appended claims.

In the drawings:

Figure l is a fragmentary perspective view ofa doorway and door with the electric mat switch of the present invention disposed in the doorway;

Fig. 2 is a plan view partially in cross section showing the details of construction of the mat switch; Fig. Bis a cross sectional view taken along the line 3-3 of Fig. 2; g Fig. 4 is a cross sectional view taken along the line 4-4 of Fig. 2;,and

Fig.5 is a cross sectional, "fragmentary perspective view of the central contactor plate of the 6 Claims. (Cl; ZEN-86) electric mat switch showing the separating elements.

The view shown in Fig. 1 of the drawings illustrates one use of the electric mat switch of the present invention. As shown in Fig. 1, a doorway lil disposed in a wall II is provided with a door 12 which is arranged for actuation toward and away from a closed position in the doorway i0 by any suitable electrically controlled mechanism (not shown). The electric mat switch [3 of the present invention is disposed at the'bottom of the doorway it] and is of sufficient length so that anyone intending to pass through the doorway l0 must step on the mat switch well in advance of the doorway and will remain on the switc'h'for an appreciable distance beyond the doorway Iii.

As best shown in Figs. 3 and 4 of the drawings, the electric mat switch 13, constructed in accord ance with the present invention, is composed of three superposed metal plates I5, l6 and H. The top two plates :5 and it are formed of flexible sheet metal which is sufiiciently flexible to bend or flex under the pressure of someone stepping on the mat but sufficiently resilient so that they will not be permanently deformed under such pressures. Suitable metal plates for use in a commercial embodiment of the electric mat switch oi the presentinvention have been made from plate aluminum sheets having a thickness of about i%". For convenience and ease of manufacture all three plates l5, l6, and l'! maybe formed of the same sheet metal, although the bottom plate I! may be of a more rigid nature, if desired, without departing from the scope of the invention.

As will be appreciated, the plates l5, l6 and I7 may be of any desired size'but in the preferred embodiment will be generally rectangular in cross section of sufiicient width to extend substantially entirely across the doorway and of sufficient length to extend a suitable distance outwardly'on either side of the door way.

"In accordance with the invention, the edge of the central metal plate It is received in an insulating channel strip 20 extending around the periphery thereof and preferably adhesively secured thereto. The channel strip 20 may be made of any suitable non-conducting material and preferably is of a slightly resilient nature. I have found, for example, that a very satisfactory channel may be composed of vinyl plastic, although other commercially available plastic materials or rubber or the like could'bejsubstituted therefor.

Disposed on the opposite surfaces of the central metal plate I6 area plurality of stag ered separating members which, in the illustration shown in the drawings, consist of a plurality of small squares 2i composed of non-conducting material which again may be vinyl plastic or any other similar material. As best shown in Fig. 5 of the drawings, the squares 2| on one side of the metal plate [6 are in staggered relationship with respect to the squares 2| on the opposite face of the plate. While the separating members have been illustrated in the drawings as being small squares 2|, it will be appreciated that the separating members could have any other desired shape, it being important only that the members on one side of the plates 16 shall be in displaced relationship with the separators on the opposite side of the plate so that they are not in vertical alignment and small enough so that they do not overlap. The squares 2! of plastic or other suitable material may be secured to the plate IE to avoid displacement in any suitable manner such as by the use of adhesive material. In one commercial embodiment of the electric mat switch of the present invention, it has been found advantageous to form the squares 2| of thin vinyl sheet material 'cut into pieces of the order of square.

The squares 2i are preferably separated into transverse and longitudinal rows which are approximately 2" or more apart. The squares in succeeding rows are staggered with respect to each other so that in any one row the squares will be separated by a distance of approximately 4" or more. However, the distance between any two squares will be considerably less and pref- 'erably not exceeding about 3".

The outer metal plates [5 and l! are then disposed on opposite sides of the central metal plate It and may be secured in position by cementing same to the periphery of the channel strip 20, the channel strip 20 being securely fixed in turn to the central plate I6 by adhesive material or the like, as previously mentioned.

In accordance with the invention, the sandwich composed of the metal plates l5, l6 and l'i is inserted within an envelope 24, preferably made of waterproof plastic material and so formed that it entirely surrounds the sandwich composed of the three metal plates. As best illustrated in Figs. 3 and 4, the envelope may be composed of a relatively'heavy tread section formed with a tapered edge portion 25 defining the periphery of the mat and forming a recess beneath the tread section 25. The sandwich composedof the metal plates l5, l6 and I! may then be disposed in the recess and fixed in place by the application of a closing sheet 21 which may be cemented or otherwise joined to the bottom of the tapered edge portion 26. While the above appears to be the most convenient way in which to form the envelope portion, it is appreciated that the envelope could be molded in one piece surrounding the sandwich formed of the metal plates [5, l6 and H. 1 l In accordance with the invention, means is provided to establish an electric connection to the central sheet l6 and a second connection jointly to the outer metalplates [Sand i1, As best shown in Figs. 2 and 3, a terminal may be secured at one edge to the central metal plate 16, there being provided an enlarged opening 3| in the lower metal plate l'l tojprovide suiiicient clearance therefor without short-circuiting. In similar manner a terminal '32 may be connected to both the outer metal plates l5 and II,

in which case the central metal plate 16 is provided with an enlarged opening 33 to receiv the terminal 32 without short-circuiting.

By establishing one connection to the central plate l6 and a second connection to the outer plates 15 and II, it will be appreciated that a contact will be established through the electric mat switch when either of the outer plates i5 or I! is brought into contact with the central plate 16. By reason of the fact that the plates [5 and I! are separated from the central plate [6 by separators 2| which are in staggered relationship, it is ensured that an electric contact will be established between one of the outer plates and the central plate regardless of where pressure is brought to bear on the mat and this contacting is accomplished primarily by the flexing of the metal plates without dependence upon highly resilient separators which normally will deteriorate when used over long periods of time. In other words, the electric mat switch will have the desired degree of sensitivity substantially uniformly throughout and will not have any areas so sensitive that contact will be established by vibration or minor pressures not intended to actuate the switch. Furthermore, the opening of the switch after the pressure is removed is caused by the resiliency of the metal sheets and not dependent on th action of resilient separating members. whereby positive action is ensured over long periods of time.

The electric mat switch of the present invention, as described above, issimple and easy to fabricate and assemble, so that it may be produced at low cost. Furthermore, the sandwich composed of the metal plates [5, l6 and I? -nor mally will not be damaged in use over long periods of time, and replacement of the upper tread section usually will be all that is required to place the electric mat switch in original new condition.

While the electric mat switch of the present invention has been described and illustrated as a single switch extending through the doorway Ii], it will be obvious that separate but abutting switches made in accordance with the invention could be provided for opposite sides of thedoorway Hl, if desired. 1 k

As many changes couldbe made in the above construction and many apparently widely d ifferent embodiments of this invention could be made without departing from the scope thereof; it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not ina limiting sense.

It is also to be understood that the language used in the followin claims is intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

I claim as my invention: I j

1. A switch of the floor mat type for controlling door actuating mechanisms and the likec'omprising three superposed generally parallelimperforate sheet metal plates, the upper two plates being sufiiciently flexible and resilient to permit flexing responsive to predetermined operating pressures to effect engagement between at least two of said three plates, means normally sepa rating the plates in said superposed parallel re;- lationship comprisingaplurality of spaced apart thin non-conductin elements disposed on each side of the intermediate plate,- the elementsfbetween the bottom and intermediate'platesbeing disposed in staggered relationship with respect to the elements between the intermediate and top plates, and means for forming one electrical connection with the intermediate plate and a second electrical connection jointly with the top and bottom plates.

2. A switch of the floor mat type for controlling door actuating mechanisms and the like comprising three three superposed generally parallel imperforate sheet metal plates, the upper two plates being suificiently flexible and resilient to permit flexing responsive to predetermined operating pressures to effect engagement between at least two of said three plates, means normally separating the plates in said superposed relationship comprising a plurality of thin spaced apart non-conductin elements of relatively small area, means for positioning the elements between the plates so that the elements between the intermediate and top plates are not in alignment vertically with the elements between the intermediate and bottom plates, and means for forming one electrical connection with the intermediate plate and a second electrical connection jointly with the top and bottom plates.

3. A switch of the floor mat type for controlling the operation of door actuating mechanisms and the like comprising three superposed generally parallel sheet metal plates, the upper two plates being sufficiently flexible and resilient to permit flexing responsive to predetermined op erating pressures to efiect engagement between at least two of said three plates, a plurality of small separating elements composed of nonconducting sheet material uniformly arranged .between the upper and intermediate plates in non-alignment vertically with similarly uniformly arranged separating elements between the intermediate and bottom plates, means for holding the plates in superposed relationship including an envelope of resilient non-conducting material receiving the superposed plates, and means forming one electrical connection with the intermediate plate and a second electrical connection jointly with the top and bottom plates.

4. A switch of the floor mat type for controlling the operation of door actuatin mechanisms and the like comprising three superposed generally parallel sheet metal plates, the upper two plates being sufliciently flexible and resilient to permit flexing responsive to predetermined operating pressures to effect engagement between at least two of said three plates, an edging strip disposed between the top and intermediate plates and between the intermediate and bottom plates at the peripheries thereof, a plurality of thin separating elements of relatively small area disposed between the top and intermediate plates and between the intermediate and bottom plates, means for retaining the elements on opposite sides of the intermediate plate at regularly spaced intervals with the elements on one side being disposed at the spaces between the elements on the other side, a cover for the plates including a tread section extending over the top plate, and means forming one electrical connection with the intermediate plate and a second elec trical connection jointly with the top and bottom plates.

5. A switch of the floor mat type for control ling the operation of door actuating mechanisms and the like comprising three superposed generally parallel sheet metal plates, the upper two plates being sufiiciently flexible and resilient to permit flexing responsive to predetermined operating pressures to effect engagement between at least two of said three plates, a plurality of small pieces of thin plastic sheet material secured to opposite sides of the intermediate plate at regularly spaced intervals but with the pieces on one side of the plate in staggered relationship with respect to the pieces on the other side, means forming one electrical connection with the intermediate plate and a second electrical connection jointly with the other two plates, and an envelope of non-conducting material for the superposed plates including a tread section extending over the top plate.

6. A switch of the floor mat type for controlling door actuating mechanism and the like comprising three superposed generally parallel imperforate sheet metal plates, means forming one electrical connection with the intermediate plate and a second electrical connection jointly with the top and bottom plates, means separating the plates in said superposed relationship comprising a first layer of regularly spaced-apart thin non-conducting elements disposed between the upper two plates and a second layer of regularly spaced-apart thin non-conducting elements disposed between the lower two plates, said first and second layers of elements being aranged in vertical disalignment and said upper two plates being suificiently resilient to permit flexing relative to each other and to the bottom plate whereby engagement is effected between said upper two plates upon the application of predetermined operating pressures in the space between adjacent elements in the first layer and normal to said plates and whereby engagement i effected between the lower two plates upon the application of predetermined operatin pressures in the space between adjacent elements in the second layer and normal to said plates.

SHELDON S. ROBY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 987,220 Dzerma Mar. 21, 1911 1,915,292 Conklin June 27, 1933 

